Devices are known in which arcuate, pivoting motion of a lever is applied to a slide element which is slidable in a straight linear path. For example, in many fluid dispensers, such as the type disclosed in U.S. Pat. No. 5,431,309 to Ophardt, issued Jul. 11, 1995, the arcuate pivoting movement of a manually operated lever is used to move a piston element of a piston pump coaxially linearly within a piston chamber forming member. One disadvantage of such previously known dispensers is that forces are applied to the piston element of the piston pump which are not merely axially directed resulting in the engagement between the piston element and the piston chamber forming member being required to resist such non-axially directed forces often leading to leakage and failure of the pump. Another disadvantage of such previously known devices is that to avoid pump failure separate mechanical arrangements must be provided to independently guide the piston element of the pump to only move linearly separate from the engagement of the piston element in the piston chamber.